JPH10257513A - Video signal processing circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain color reproduction optimum for all hues by respectively independently changing the hues even in case of colors in symmetric relation on a vector diagram by changing the coefficient of color matrix circuit. SOLUTION: An R-G positive area signal outputted from a 1st negative/ positive separator circuit 100 is inputted to an ap-fold circuit 102 and a cp-fold circuit 106. An R-G negative area signal is inputted to an an-fold circuit 103 and a cn-fold circuit 107. A B-G positive area signal outputted from a 2nd positive/negative separator circuit 101 is inputted to a bp-fold circuit 104 and a dp-fold circuit 108. A B-G negative area signal is inputted to a bn-fold circuit 105 and a dn-fold circuit 109. Thus, only the hue on one side with R-Y and B-Y axes as borders is changed even in case of any coefficient. Namely, when the coefficient is changed for changing one determined hue, the hues symmetric in respect to an origin are not changed at all.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal processing circuit.

[0002]

2. Description of the Related Art In recent years, consumer video integrated cameras have become remarkably widespread, and in recent years there has been a particularly strong demand for higher image quality. In particular, it can be said that improvement in color reproducibility is most strongly desired.

Hereinafter, a conventional video signal processing circuit will be described. FIG. 6 is a block diagram showing a color matrix circuit configuration in a conventional video signal processing circuit, FIG. 7 is a waveform diagram showing signal waveforms at various parts in the block diagram of FIG. 6, and FIG. FIG. 5 is a vector diagram in which the RY signal level is coordinated on the vertical axis. 6, reference numeral 200 denotes an R signal input terminal to which an R (red) signal is input; 201, a G signal input terminal to which a G (green) signal is input; and 202, a B signal input to which a B (blue) signal is input Terminal, 203 is an RG processing circuit for subtracting the G signal from the R signal, 204 is a BG processing circuit for subtracting the G signal from the B signal, and 205 is a coefficient a for the signal from the RG processing circuit 203.
A multiplying circuit for multiplying the signal from the BG processing circuit 204 by b;
A c-multiplier circuit for multiplying the signal from 3 by c, a d-multiplier circuit 208 for d-multiplying the signal from the BG processing circuit 204, and 209 a
A first addition circuit for adding the output signal of the multiplication circuit 205 and the output signal of the b multiplication circuit 206, and a second addition circuit 210 for adding the output signal of the c multiplication circuit 207 and the output signal of the d multiplication circuit 208
An R-Y signal output terminal 211 for outputting the R-Y signal output from the first addition circuit 209 to the outside;
A BY signal output terminal 212 outputs the BY signal output from the second adding circuit 210 to the outside.

In FIG. 7, 220 is an R signal, 221 is a G signal, 222 is a B signal, 223 is an RG signal, 224
Represents a BG signal, 225 represents an RY signal, and 226 represents a BY signal. In FIG. 8, reference numerals 232 to 237 indicate red (R), yellow (Ye), green (G), cyan (Cy), blue (B), and magenta (Ma) of the color bar signal, respectively.

The operation of the conventional video signal processing circuit configured as described above will be described below.

First, the R signal input from the R signal input terminal 200 and the G signal input from the G signal input terminal 201 are input to an RG processing circuit 203 and subjected to a subtraction process. Further, the B signal input from the B signal input terminal 202 and the G signal input from the G signal input terminal 201 are input to the BG processing circuit 204 and subjected to a subtraction process.
The output signal of the R-G processing circuit 203 is a
The output signal of the BG processing circuit 204 is input to the b multiplication circuit 206 and the d multiplication circuit 208.

Here, a multiplication circuit 205 to d multiplication circuit 208
Will be described. First, a luminance signal (hereinafter, referred to as a Y signal) Y is

[0008]

(Equation 3)

[0009] The RY signal and the BY signal are

[0010]

(Equation 4)

Is calculated. Therefore, the a-fold circuit 20
The coefficient a of 5 is 0.70, and the coefficient b of the b multiplication circuit 206 is −
0.11, the coefficient c of the c-fold circuit 207 is -0.30, and the coefficient d of the d-fold circuit 208 is 0.89.

Then, the output signals of the RG processing circuit 203 and the BG processing circuit 204 are multiplied by an a multiplication circuit 205 to a d multiplication circuit 208 based on the aforementioned coefficients. a times circuit 2
05 and the output signal of the b multiplication circuit 206 are
09 to obtain an RY signal. The output signals of the c-multiplying circuit 207 and the d-multiplying circuit 208 are added by the second adding circuit 210 to obtain a BY signal. The RY signal obtained by the first addition circuit 209 is output to the outside from an RY signal output terminal 211, and the BY signal obtained by the second addition circuit 210 is a BY signal output terminal. 212 is output to the outside.

Generally, the coefficients a to d are fixed at the above values. Even in a video camera, it is originally assumed that the coefficients are fixed. The color spectral characteristics of the optical system are adjusted so that a predetermined light source and a predetermined color are at predetermined positions on a vector diagram. Also,
If the light source changes, a color temperature conversion filter or the like is attached to the front of the lens to change the spectral characteristics and take measures. However, in a consumer video camera, the optical system is designed to be as low-cost and compact as possible, so the color spectral characteristics in the strict sense are not matched, and a color temperature conversion filter for changes in the light source is not used. By changing the above-described coefficients, variations in the spectral characteristics of the optical system are absorbed, and changes in color reproducibility in response to changes in the light source are made.

FIG. 9 shows a change in each hue when the values of the coefficients a to d are changed. FIG. 9A shows the movement of the hue when the coefficient a is increased, and FIG. 9B shows the movement of the hue when the coefficient b is increased.
9 shows the shift of the hue when the coefficient c is increased.
(D) shows the shift of the hue when the coefficient d is increased. As shown by the arrows in the respective drawings, it can be seen that they move diametrically opposite with respect to the RY axis and the BY axis. It can also be seen that the two points whose origins are symmetrical move diametrically with respect to any change in the coefficients a to d.

[0015]

However, in the above-described conventional configuration, when the coefficient is changed for the purpose of changing a certain hue, the hue whose origin is symmetrical also changes. However, there is a problem in that, when an attempt is made to add lean to a flesh color, the blue-based color, which is a symmetrical color of yellow, shifts in the cyan direction, and the overall color reproduction balance is lost.

The present invention solves the above-mentioned conventional problems. Even if the colors have a symmetric relationship on a vector diagram, the hues can be changed independently, and the optimum color reproduction can be achieved for all hues. It is an object to provide an obtained video signal processing circuit.

[0017]

In order to achieve the above object, a video signal processing circuit according to the present invention is a video signal processing circuit for obtaining a color difference signal RY signal and a BY signal from an RGB signal. R-G for subtracting the G signal from the R signal
A processing circuit for subtracting the G signal from the input B signal;
-G processing circuit; a first positive / negative separation circuit for separating an output signal of the RG processing circuit into a signal in a positive region and a signal in a negative region; A second positive / negative separating circuit for separating the signals into positive and negative signals; a first predetermined multiplying circuit for multiplying the positive and negative area signals from the first positive / negative separating circuit by a predetermined number; and a positive and negative signals from the second positive / negative separating circuit. A second predetermined multiplying circuit for multiplying the area signal and the negative area signal by a predetermined number; a third predetermined multiplying circuit for multiplying the positive and negative area signals from the first positive / negative separating circuit by a predetermined number; A fourth predetermined multiplying circuit for multiplying the positive area signal and the negative area signal from the positive / negative separation circuit by a predetermined number, and an output signal of the first and second predetermined multiplying circuits for adding the R-Y signal The output signals of the first adder circuit and the third and fourth predetermined multiplying circuits are added to perform the B It is obtained by a second adding circuit for outputting a Y signal.

With this configuration, it is possible to independently change the hues of colors having a symmetrical relationship on the vector diagram, and to obtain a video signal processing circuit capable of obtaining optimum color reproduction for all hues.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claims 1 to 3 of the present invention is a video signal processing circuit for obtaining a color difference signal RY signal and a BY signal from an RGB signal. An R-G processing circuit for subtracting the G signal from
A BG processing circuit for subtracting a G signal from a signal;
A first positive / negative separation circuit for separating an output signal of the G processing circuit into a signal in a positive region and a negative region, and a second positive / negative separation for separating the output signal of the BG processing circuit into a signal in a positive region and a negative region A first predetermined multiplying circuit for multiplying a positive area signal and a negative area signal from the first positive / negative separation circuit by a predetermined number; A second predetermined multiplying circuit, a third predetermined multiplying circuit for multiplying the positive area signal and the negative area signal from the first positive / negative separation circuit by a predetermined number, and a positive area signal from the second positive / negative separation circuit. A fourth predetermined multiplying circuit for multiplying the negative area signal by a predetermined number, and an output signal of the first and second predetermined multiplying circuits being added to perform R-
A first adding circuit for outputting a Y signal;
And a second adder circuit for adding the output signal of the predetermined multiplication circuit to output the BY signal. With this configuration, even if the colors have a symmetrical relationship on the vector diagram, the hues are changed independently. Optimum color reproduction can be obtained for all hues.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 is a block diagram showing a configuration of a color matrix circuit in a video signal processing circuit of the present invention, FIG. 2 is a waveform diagram showing signal waveforms at various parts in the block diagram of FIG. Is an R signal input terminal to which an R (red) signal is input; 201 is a G signal input terminal to which a G (green) signal is input; 202 is a B signal input terminal to which a B (blue) signal is input; RG processing circuit for subtracting a G signal from a signal; 204, a BG processing circuit for subtracting a G signal from a B signal; 100 and 101, output signals of an RG processing circuit 203 and a BG processing circuit 204; First and second positive / negative separating circuits for separating into a positive region and a negative region,
102 is an ap multiplying circuit for multiplying the positive area signal of the first positive / negative separating circuit 100 by a factor ap, 103 is the first positive / negative separating circuit 1
An an multiplication circuit that multiplies the negative area signal of 00 by a factor ap
The multiplier 102 and the an multiplier 103 constitute a first predetermined multiplier. Reference numeral 104 denotes a bp multiplying circuit for multiplying the positive area signal of the second positive / negative separating circuit 101 by a coefficient bp, and 105 denotes a bn multiplying circuit for multiplying the negative area signal of the second positive / negative separating circuit 101 by a coefficient bp. second with the bn multiplying circuit 105
Of the predetermined multiplication circuit. Reference numeral 106 denotes a cp multiplication circuit for multiplying the positive area signal of the first positive / negative separation circuit 100 by a coefficient cp.
7 represents the negative region signal of the first positive / negative separation circuit 100 with a coefficient cp
Cp multiplication circuit 106 and cn multiplication circuit 1
07 constitutes a third predetermined multiplier circuit. 108 is a dp that multiplies the positive area signal of the second positive / negative separation circuit 101 by a factor dp.
A multiplying circuit 109 is a dn multiplying circuit for multiplying the negative area signal of the second positive / negative separating circuit 101 by a factor dp. 2
09 is a first addition circuit for adding the output signals of the ap multiplication circuit 102 to the bn multiplication circuit 105, and 210 is the cp multiplication circuit 106
A second addition circuit 211 for adding the output signals of the .about.dn multiplier circuit 109;
An RY signal output terminal for outputting the Y signal to the outside, and a BY signal output terminal 212 for outputting the BY signal output from the second addition circuit 210 to the outside.

In FIG. 2, 220 is an R signal, 221 is a G signal, 222 is a B signal, 223 is an RG signal, 224
Is a BG signal, 120 is a signal in the positive region of the RG signal, 1
21 is a signal in the same negative region, 122 is a signal in the positive region of the BG signal, 123 is a signal in the same negative region, 225 is an RY signal,
226 is a BY signal.

The operation of the video signal processing circuit according to the present embodiment configured as described above will be described below.

First, the R signal input from the R signal input terminal 200 and the G signal input from the G signal input terminal 201 are input to the RG processing circuit 203 and subjected to subtraction processing. Further, the B signal input from the B signal input terminal 202 and the G signal input from the G signal input terminal 201 are input to the BG processing circuit 204 and subjected to a subtraction process.
The output signal of the RG processing circuit 203 is separated into a positive area signal and a negative area signal by a first positive / negative separation circuit 100, and the output signal of the BG processing circuit 204 is similarly separated by a second positive / negative separation circuit 101. The signal is separated into a positive region signal and a negative region signal.

The R-G positive area signal output from the first positive / negative separation circuit 100 is input to an ap multiplication circuit 102 and a cp multiplication circuit 106. The negative region signal of the RG is an
The signal is input to the doubler 103 and the cn multiplier 107. Second
Is output from the positive / negative separation circuit 101 to the bp multiplication circuit 104 and the dp multiplication circuit 108. The BG negative area signal is obtained by the bn multiplication circuit 105 and d
The signal is input to the n-times circuit 109.

Here, the signal in the positive region of the RG signal is represented by (R
-G) H, the signal in the negative region is (RG) L, the signal in the positive region of the BG signal is (BG) H, and the signal in the negative region is (B).
-G) When L, the RY signal and the BY signal are

[0026]

(Equation 5)

And the ap multiplication circuit 102 to the dn multiplication circuit 1
The coefficients ap to dn of 09 are

[0028]

(Equation 6)

Is as follows. Then, the AP multiplication circuit 102
To the bn multiplying circuit 105 by the first adding circuit 209
To generate the RY signal, and the cp multiplication circuits 106 to d
The output signal of the n-fold circuit 109 is added by a second adding circuit 210 to generate a BY signal. The RY signal is output from the RY signal output terminal 211 to the outside, and the BY signal is
The signal is output from the Y signal output terminal 212 to the outside.

Next, the movement of the hue when the values of the coefficients ap to dn are changed will be described. FIG. 3 shows a coefficient ap,
FIG. 3A is a vector diagram showing a change when the values of bp, cp, and dp are changed. FIG. 3A is a coefficient ap, and FIG.
p, FIG. 3C shows the shift of the hue when the coefficient cp is increased, and FIG. 3D shows the shift of the hue when the coefficient dp is increased. FIG. 4 is a vector diagram showing a change when the values of the coefficients an, bn, cn, and dn are changed. FIG. 4A shows the coefficient an, FIG.
4C shows the coefficient bn, FIG. 4C shows the coefficient cn, and FIG. 4D shows the hue shift when the coefficient dn is increased. As is clear from FIGS. 3 and 4, for any coefficient, only one side of the hue changes with respect to the RY axis and the BY axis. That is, when the coefficient is changed for the purpose of changing one fixed hue, the hue whose origin is symmetric does not change at all.

Embodiment 2 Hereinafter, Embodiment 2 of the present invention will be described with reference to the drawings.

FIG. 5 is a block diagram showing the configuration of the video signal processing circuit according to the present embodiment. 5, the same components as those in the configuration of FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. Reference numeral 140 denotes a coefficient control unit for changing and controlling the coefficients of the ap multiplication circuit 102 to the dn multiplication circuit 109.

In the case of this configuration, when it is necessary to optimize the color reproducibility due to a change in color temperature or the like, the coefficients of the ap multiplying circuit 102 to the dn multiplying circuit 109 are arbitrarily determined by a control signal input from the coefficient control unit 140. If you control the change to the value of
Can respond to it.

[0034]

As described above, according to the present invention, the variation of the spectral characteristics of the optical system can be absorbed by changing the coefficient of the color matrix circuit of the video camera, and the color reproducibility can be changed with the change of the light source. However, it has an excellent effect that optimum color reproduction can be obtained for all hues.

[Brief description of the drawings]

FIG. 1 is a block diagram of a video signal processing circuit according to Embodiment 1 of the present invention.

FIG. 2 is a waveform chart showing signal waveforms at various parts in the circuit of the embodiment.

FIG. 3 is a vector diagram showing a change in hue when coefficients ap to dp are changed in the embodiment.

FIG. 4 is a vector diagram showing a change in hue when coefficients an to dn are changed in the embodiment.

FIG. 5 is a block diagram of a video signal processing circuit according to a second embodiment of the present invention.

FIG. 6 is a block diagram of a conventional video signal processing circuit.

FIG. 7 is a waveform chart showing signal waveforms at various parts in a conventional video signal processing circuit.

FIG. 8 is a vector diagram showing hues in a conventional video signal processing circuit.

FIG. 9 is a vector diagram showing a change in hue when coefficients a to d in the conventional video signal processing circuit are changed.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 first positive / negative separation circuit 101 second positive / negative separation circuit 102 ap multiplication circuit 103 an multiplication circuit 104 bp multiplication circuit 105 bn multiplication circuit 106 cp multiplication circuit 107 cn multiplication circuit 108 dp multiplication circuit 109 dn multiplication circuit 203 R-G Processing circuit 204 BG processing circuit 209 First addition circuit 210 Second addition circuit

Claims (3)

[Claims] 1. An image signal processing circuit for obtaining a color difference signal RY signal and a BY signal from an RGB signal, wherein the R-G processing circuit subtracts a G signal from an input R signal. A BG processing circuit for subtracting the G signal from the B signal;
A first positive / negative separating circuit for separating an output signal of the RG processing circuit into a positive region and a negative region signal, and a second positive / negative separating circuit for separating the output signal of the BG processing circuit into a positive region and a negative region signal A positive / negative separating circuit, a first predetermined multiplying circuit for multiplying a positive region signal and a negative region signal from the first positive / negative separating circuit, and a positive region signal and a negative region signal from the second positive / negative separating circuit A second predetermined multiplying circuit for multiplying the positive domain signal and the negative domain signal from the first positive / negative separating circuit by a predetermined factor.
A predetermined multiplying circuit, a fourth predetermined multiplying circuit for multiplying the positive area signal and the negative area signal from the second positive / negative separating circuit, and an output processing of the first and second predetermined multiplying circuits A first adder circuit for outputting the RY signal;
And the output signal of the fourth predetermined multiplying circuit is added,
A video signal processing circuit comprising: a second addition circuit that outputs a Y signal. 2. A video signal processing circuit for obtaining a color difference signal RY signal and a BY signal from an RGB signal, wherein the RGB signal processing circuit subtracts a G signal from an input R signal. A BG processing circuit for subtracting the G signal from the B signal;
A first positive / negative separating circuit for separating an output signal of the RG processing circuit into a positive region and a negative region signal, and a second positive / negative separating circuit for separating the output signal of the BG processing circuit into a positive region and a negative region signal A positive / negative separating circuit, a first predetermined multiplying circuit for multiplying a positive region signal and a negative region signal from the first positive / negative separating circuit, and a positive region signal and a negative region signal from the second positive / negative separating circuit A second predetermined multiplying circuit for multiplying the positive domain signal and the negative domain signal from the first positive / negative separating circuit by a predetermined factor.
A predetermined multiplying circuit, a fourth predetermined multiplying circuit for multiplying the positive area signal and the negative area signal from the second positive / negative separating circuit, and an output processing of the first and second predetermined multiplying circuits A first adder circuit for outputting the RY signal;
And the output signal of the fourth predetermined multiplying circuit is added,
A second addition circuit for outputting a Y signal.
A video signal processing circuit comprising: a coefficient control unit for changing and controlling a coefficient of the fourth predetermined multiplier circuit. 3. The first to fourth predetermined multiplying circuits output the positive area signal from the first positive / negative separation circuit to (R−G) H and the negative area signal from the first positive / negative separation circuit to (R−G). G) L, when the positive area signal from the second positive / negative separating circuit is (BG) H and the negative area signal from the second positive / negative separating circuit is (BG) L, the color difference signal RY Is given by And the color difference signal BY is calculated by the following equation. 3. The video signal processing circuit according to claim 1, wherein the calculation is performed by using the coefficients ap to dn calculated from.